The Gibbs Free Energy Calculator is a powerful tool designed to calculate the change in Gibbs free energy (ΔG) for chemical reactions and thermodynamic processes. Gibbs free energy determines the spontaneity of a reaction, predicting whether a process can occur naturally under given conditions of temperature and pressure.
This calculator makes complex thermodynamic calculations fast, precise, and user-friendly, helping students, chemists, and engineers analyze reactions efficiently.
Gibbs Free Energy (G) is a thermodynamic quantity that combines enthalpy (H), entropy (S), and temperature (T) to predict the direction of chemical processes.
Key points:
ΔG < 0 → reaction is spontaneous
ΔG = 0 → reaction is at equilibrium
ΔG > 0 → reaction is non-spontaneous
Calculated using the relation between enthalpy, entropy, and temperature
Essential for chemistry, biochemistry, and chemical engineering
Gibbs free energy is a central concept in predicting reaction feasibility, optimizing industrial processes, and understanding biological pathways.
Gibbs Free Energy Change Formula:
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ΔG = ΔH − T × ΔS
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Where:
ΔG = Gibbs free energy change (J/mol or kJ/mol)
ΔH = Enthalpy change (J/mol or kJ/mol)
T = Absolute temperature (K)
ΔS = Entropy change (J/mol·K)
Standard Gibbs Free Energy Relation to Equilibrium Constant:
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ΔG° = −R × T × ln(K)
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Where:
ΔG° = Standard Gibbs free energy (J/mol)
R = Universal gas constant (8.314 J/mol·K)
T = Temperature in Kelvin
K = Equilibrium constant
Formula Highlight: Both formulas are framed in the calculator interface for better usability and quick reference.Problem: Calculate ΔG for a reaction at 298 K with ΔH = −100 kJ/mol and ΔS = −200 J/mol·K.
Step 1: Convert entropy to kJ/mol·K
ΔS = −200 J/mol·K ÷ 1000 = −0.2 kJ/mol·K
Step 2: Apply formula ΔG = ΔH − TΔS
ΔG = −100 − 298 × (−0.2)
ΔG = −100 + 59.6 ≈ −40.4 kJ/mol
Step 3: Interpret result
ΔG < 0 → reaction is spontaneous at 298 K